Xiuhtezcatl Martinez is the 16 year-old activist who made headlines earlier this year when he spearheaded a class action lawsuit against President Obama and various government agencies, alleging that their failure to halt climate change posed a threat to the next generation of Americans. Now, Martinez is back with a message for the 2016 presidential candidates: adopt climate change as a top priority and find solutions fast. He has sponsored a petition to collect signatures from kids who are too young to vote in the upcoming election but are desperate for their voices to be heard.

Martinez hasn’t let his young age or inability to vote get in the way of working for a better planet. Now 16, he is an accomplished speaker, hip-hop artist, and the Youth Director of Earth Guardians, a nonprofit comprised of young activists seeking to protect the environment. Martinez has been speaking at national and international events since he was just six years-old, pleading with government officials to act with future generations in mind. He hopes this new petition will send a strong message to all the presidential candidates about the urgency of combating climate change. “I can’t vote in November, but my future is on the ballot,” he wrote in the letter, addressed to Donald Trump, Hillary Clinton, Bernie Sanders and the remaining 2016 presidential candidates. “My generation demands to know the answer to this question: What are you going to do about the climate crisis?”

Trump, who has all but secured the Republican party nomination, is an unapologetic climate denier. He has repeatedly called climate change a “hoax,” blaming the Chinese for manipulating global fears. Environmental experts have already voiced concerns that a Trump presidency would undo the United Nations climate change agreement which calls for vast reductions in carbon emissions, more investments in renewable energy, and a host of environmental protections for the Earth and its inhabitants. In the Democratic party, the outlook is more hopeful, but while Clinton has expressed lofty goals for new solar power installations, there are concerns about how realistic those plans might be, especially in the absence of tight restrictions on fossil fuels.

The petition further urges the nation’s next president to make a public commitment to uphold the UN climate change agreement, which will clearly be a tough sell for the Trump camp. Yet, with the respective party conventions just weeks away, Martinez remains steadfast in pushing for results. “My generation demands you act with even greater urgency,” the petition states. “We can end the use of fossil fuels by 2026, and we need the next president to make that a reality.”